The present invention relates to an operating- and braking-assistance device for wheelchairs, which is attachable to the frame of a wheelchair. Such assistance devices facilitate the sliding or rolling of a person sitting in a wheelchair on inclined or on rough, difficult-to-maneuver surfaces. With these individual sliding aids, support of the braking process on steep terrain is also possible. Known sliding and brake aids therefore have either a friction wheel that is motorized and able to be pressed down on the surface or a hub drive for the wheels of the wheelchair. The assistance devices with friction wheels have the disadvantage that the friction wheel must lie on the ground with a relatively large downward pressure, in order to be sufficiently operable. Hub drives are expensive to construct and have an unfavorable gear ratio, so that, in practice, a gear drive is required.
The present invention addresses the underlying problem of making a sliding and braking aid for wheelchairs, which has high operational efficiency and power with a minimal expenditure of force, and which is easy to mount and disassemble.
The above problem is resolved with an operating- and braking-assistance device for wheelchairs, which is attachable to the frame of a wheelchair, and which according to the present invention, has at least one pinion that is motorized to be driveable both directions, which engages on an internal gear on the rim of a wheel of the wheelchair. The pinion engaging on the internal gear makes possible a large mechanical xe2x80x9cstep-upxe2x80x9d also without gears. The device can be easily mounted and dismounted, whereby the internal gear can remain on the wheel.
In order to maintain the most uniform driving and braking conditions, advantageously an internal gear, which is engagable with a pinion, is securable to each wheel. Both pinions can thereby be driven by a common motor shaft.
The internal gear can have an attachment section running about its radially outer side, the attachment section having a hook-shaped cross section and being suspendable on the rim of the wheel. This attachment section, which is preferably elastically deformable, can be easily suspended in the rim, when air is let out of the tire of the wheel. Subsequently, the tire is again pumped up and in this manner, also the attachment section is braced with the rim. The internal gear, then, is therefore very simple to attach later to the wheel of a wheelchair. It can also remain with disassembled sliding and brake devices, since it does not prevent the normal hand operation of the wheelchair via a grip ring or screw.
Based on the favorable transmission ratio, the pinion can be directly driven by the motor shaft. In the event it is desired or necessary, of course, however, also a gear unit and differential can be provided between the motor and pinion.